[mayanour4]

Makes detector execution cancellable, time-bounded, and easier to diagnose. The extension now clears stale results after cancelled, failed, or superseded runs and provides actionable failure details in the Output channel.

Testing Note:

• Verified cancellation using a deliberately slow Java process.
• Confirmed the Problems panel clears previous diagnostics after cancellation.
• Verified missing-Java failure guidance and technical Output details.
• Ran automated tests covering cancellation, timeout, missing Java, and missing JAR.
• Passed TypeScript checks, compilation, all 10 regression fixtures, and VSIX packaging.
• Screenshots demonstrating cancellation, cleared stale results, timeout documentation, and missing-Java reporting are attached to the ticket.

Closes #57.